In general, modern exhaust-gas turbochargers are equipped with an electric or pneumatic actuator which is required for adjusting a valve device on the turbine (wastegate). The actuator is activated via a motor-actuated control and therefore moves a control rod. The control rod which is moved substantially linearly acts on a lever arm which converts the movement into a rotation and at the same time transmits same to the flap plate. These kinematics ensure that the mass flow is controlled by the wastegate valve. However, so that the kinematics function without friction all of the components have to have a minimum play and have to be freely movable. The minimum play is also required in order to compensate for thermal distortions and manufacturing tolerances.
However, because of the axial and radial play between the flap plate and the lever arm, which play is required in order to compensate for tolerances, annoying acoustic noises, for example rattling or chattering, which are distinct to a greater or lesser extent depending on the engine operating point, but always signify a loss of comfort, are produced during operation because of the engine vibrations and the pulsating mass flow of exhaust gas. In addition, this component play causes increased wear and leakage at said component over the service life.
In order to reduce this, a type of ball-and-socket joint connection is known from DE 10 2013 214 665 A1, with a lever arm and a flap plate, which is connected thereto, for closing an opening of the valve. The flap plate has a concave recess, wherein the lever arm has a spherical region which is formed in a complementary manner with respect to the concave recess of the flap plate and with which said lever arm engages in the concave recess of the flap plate. A holding device with two holding elements and a connecting element connecting the holding elements is provided on the flap plate, said holding device engaging around the spherical region of the lever arm and, as a result, securing the flap plate on the lever arm. By this means, in particular chattering noises are intended to be avoided. The connecting element is welded here to the holding elements, which is technically complicated and expensive.